Recombinant iron uptake proteins

ABSTRACT

Neisserial iron uptake proteins including transferrin binding protein A (TbpA) and B (TbpB) in both full length form and as immunogenic fragments are made recombinantly. A non-neisserial cell expresses a TbpA which is extracted from the cell under mild conditions and retains substantially the antigenicity of native TbpA on its surface. TbpB is also made recombinantly and both TbpA and TbpB are included in vaccine compositions.

[0001] The present invention relates to recombinant iron uptake proteins, in particular recombinant transferrin binding proteins and vaccines based thereon.

[0002] Meningococcal meningitis is of particular importance as a worldwide health problem and in many countries the incidence of infection is increasing. Neisseria meningitidis (the meningococcus) is the organism that causes the disease and is also responsible for meningococcal septicaemia, which is associated with rapid onset and high mortality, with around 22% of cases proving fatal.

[0003] The meningococcal transferrin receptor is a suitable vaccine component and made up of two types of component protein chain, transferrin binding protein A (TbpA) and TbpB. The receptor complex is proposed to be formed from a dimer of TbpA which associates with a single TbpB. Epitopes present in TbpA are known to be masked within the interior of the protein. Vaccines against meningococcal disease based on TbpB from one strain alone show some cross reactivity and there is evidence of a cross-reactive immune response in rabbits immunised with TbpB alone.

[0004] Obtaining Tbps from natural bacterial sources carries the difficulty of obtaining adequate quantities for industrial vaccine production, together with the near impossibility of culturing large volumes of meningococci under safe conditions. It would therefore be desirable to produce the Tbps recombinantly.

[0005] Recombinant production of TbpB is known, providing large amounts of the recombinant protein, extracted from inclusion bodies using conventional techniques.

[0006] TbpA is one of a family of proteins referred to as TonB-dependent outer membrane receptors, due to their physical location in the Neisserial membrane and their functional interaction with TonB. TbpB is not TonB-dependent but is added to this group for the purpose of the present application due to its interaction with TbpA in forming the transferrin receptor. This group thus includes Tbps and lactoferrin binding proteins and will be referred to as a whole as the iron uptake proteins.

[0007] A difficulty in known methods of recombinantly producing iron uptake proteins is that the resultant proteins are recovered in non-native conformations, undesirable in vaccines based thereon. Another problem is that some iron uptake proteins can not hitherto be made recombinantly, and this is notably the case for TbpA.

[0008] Recombinant production of TbpB in E. coli is known from Legrain et al, “Production of lipidated meningococcal transferrin binding protein 2 in Escherichia coli”, Protein Expression and Purification 6, 570-578 (1995). This describes an expression system for production of TbpB and fermenter cultures but does not describe TbpB purification. The TbpB is said to be located in the insoluble fraction of the cellular extracts, indicating that the protein is in an insoluble form, i.e. in inclusion bodies.

[0009] Lissolo et al, in Infection and Immunity, 63:884-90 (1995) describes purification of TbpB from the meningococcus using denaturing conditions.

[0010] Renauld-Mongenie et al, in J Bacteriol., 179:6400-7 (1997) describes expression of TbpB as maltose binding protein-TbpB fusions, and then purification in 3M Urea buffer using the affinity system for maltose binding proteins.

[0011] Gonzalez et al, in Microbiology, 141:2405-16 (1995) describes how Actinobacillus pleuropneumoniae TbpA and TbpB are eluted from transferrin Sepharose with a denaturing buffer containing SDS and mercaptoethanol.

[0012] Palmer et al, in FEMS Microbiology Letters, volume 110, pp 139-146, 1993, purport to describe TbpA expression in E. coli. However, Palmer et al were not able to recover TbpA in a functional form.

[0013] The invention has as an object the provision of improved methods of production of iron uptake proteins, in particular transferrin binding proteins, and specific objects of providing alternative and/or improved recombinant production of such proteins and of providing recombinant production of TbpA. A further object of the invention is to provide improved preparation of vaccines containing transferrin binding proteins.

[0014] A first aspect of the invention is based upon successful recombinant expression of transferrin binding proteins and confirmation that the transferrin binding proteins expressed retain the antigenicity of native transferrin binding proteins, as evidenced by ability of the recombinantly produced proteins to bind human transferrin and confer protective immunity against challenge by meningococci.

[0015] Accordingly, the invention provides a non-neisserial cell expressing a neisserial iron uptake protein, wherein the iron uptake protein can be extracted from the cell under mild conditions and retains substantially the antigenicity of native iron uptake protein.

[0016] The invention further provides a non-neisserial cell expressing a neisserial iron uptake protein wherein the iron uptake protein is located in a surface membrane of the cell.

[0017] In a specific embodiment, the invention provides a non-neisserial cell expressing a Neisserial transferrin binding protein (Tbp) wherein said Tbp can be extracted from the cell under mild conditions and retains substantially the antigenicity of native TbpA.

[0018] The invention additionally provides a cell overexpressing a neisserial iron uptake protein.

[0019] The iron uptake protein is preferably selected from the group consisting of transferrin binding proteins (Tbps), lactoferrin binding proteins (Lbps), haemoglobin binding protein, enterobactin binding protein, vibriobactin binding protein, ferric siderophore binding protein, heme binding protein, hemin binding protein, chrysobactin binding protein, hydroxymate binding protein and pseudobactin binding protein—some of these proteins also being referred to as “receptor”s rather than “binding protein”s.

[0020] Also provided is a cell which expresses a neisserial Tbp, wherein the yield of said Tbp is at least 4 mg per litre of culture, preferably at least 7 mg and more preferably at least 10 mg. In these embodiments of the invention, the cell is preferably bacterial and the Tbp can be A or B.

[0021] TbpA is expressed in an example at a yield of from about 6 to about 12 mg per litre of culture.

[0022] In addition, the invention is hence of application to overexpression of Tbps in organisms that are known to express Tbps. In this sense, “overexpression” is intended to mean expression in a cell of a protein that is not in nature expressed in that cell as well as expression in a cell of a protein that is expressed in that cell in nature but at a lower level, the invention in this latter case resulting in expression of that protein at a higher level. Overexpression in, for example, commensal neisseria is of use as outer membrane preparations enriched in Tbps or containing heterologous Tbps can be obtained therefrom, and are advantageously used in vaccines. A specific embodiment lies in a commensal Neisseria expressing an iron uptake protein from a pathogenic Neisseria, especially one expressing TbpA and/or TbpB.

[0023] In use of the invention, TbpA has been found to be expressed so that it is located on or associated with the cell surface, and thus expressed with any necessary trafficking signals so that the TbpA gene product ends up on or associated with the surface. Further, the TbpA expressed can easily be extracted using mild conditions, such as using a conventional detergent extraction method, whilst retaining the antigenicity and hence the properties relevant to vaccinating use of native protein.

[0024] By mild conditions it is meant that recombinant protein can be extracted without the need to denature and then renature the protein. If the protein were located in inclusion bodies there would be a need to employ more severe recovery techniques, typically involving denaturing of the protein. However, an advantage of the invention is that the protein is surface bound or associated, and is not sequestered in inclusion bodies, so extraction does not require this denaturing, with its consequent damage to the confirmation of the protein and potential loss of key epitopes.

[0025] It is an option also to produce TbpB recombinantly, and thus the invention also provides a cell expressing, recombinantly, both TbpA and TbpB. This confers the advantage of using a single cell for two important vaccine components.

[0026] In an example below, TbpB has been expressed at a yield of from about 7 to about 32 mg per litre of culture.

[0027] The desired antigenicity in, by way of example, the TbpA and TbpB obtained from cells of the invention is antigenicity that stimulates an immune response against Tbp and organisms expressing Tbp. The proteins obtained in examples of the invention have been tested in animal models and the extracted Tbp demonstrated to confer protection against subsequent challenge by meningococci, this confirming Tbp in a substantially native confirmation has been obtained. This has the advantage of providing an efficient route of recombinant production of these proteins for subsequent use for example in further structure-function analysis and pharmaceutical, particularly vaccine, applications.

[0028] The invention also relates to methods of iron uptake protein production and provides, in a second aspect, a method of producing an iron uptake protein by expressing a recombinant iron uptake protein gene in a non-neisserial cell host such that the protein is expressed and translocated to a surface membrane of the host. The protein can then be extracted using mild conditions.

[0029] The invention also relates specifically to methods of Tbp production and provides a method of producing a neisserial transferrin binding protein (Tbp) comprising:

[0030] a. expressing a recombinant neisserial Tbp gene in a non-neisserial host such that Tbp protein is expressed and translocated to the cell membrane;

[0031] b. under mild conditions, extracting Tbp protein.

[0032] The method can also include expressing recombinant neisserial TbpA and TbpB genes, in the same culture and optionally in the same cell.

[0033] A still further embodiment of the invention resides in a method of producing a transferrin binding protein (Tbp) from a pathogenic Neisseria, comprising expressing a gene encoding the Tbp in a commensal Neisserial host such that Tbp protein is translocated to an outer surface membrane of the commensal host, extracting the Tbp under mild conditions, and, optionally, purifying said Tbp protein. An outer membrane vesicle preparation is suitable, for example for vaccine preparation, and a N. meningitidis gene expressed in N. lactamica is particularly suitable.

[0034] The Tbp is suitably extracted by solubilising membrane associated Tbp in a non-ionic detergent solution, yielding good quantities of Tbp in native form and which has been demonstrated to be both functional and protective against meningococcal challenge. A number of non-ionic detergents are suitable for the extraction, including one chosen from an alkyl glucoside; n-octyl-β-D-glucopyranoside; TRITON® X100; ELUGENT®; dodecyl-maltoside; and n-octyl-β-D-maltoside. The extraction preferably includes a low energy homogenisation step, conveniently preceded by using apparatus such as a bead-beating apparatus, though other such apparatus are also available, to break up cells and isolate cell membranes.

[0035] To obtain the desired location of expressed protein, an expression construct is preferably used that combines a nucleotide sequence encoding the iron uptake protein with a leader sequence directing the expressed protein to a surface membrane of the host, this construct forming a further embodiment of the invention. The leader sequence is suitably a neisserial leader sequence, and good results have been obtained in specific examples below where the neisserial iron uptake protein is expressed using its own neisserial leader sequence. TbpA has been expressed using the TbpA leader. Another option is to use a host leader sequence that directs translocation of the recombinant product to a surface membrane of the host, for example an E. coli leader if the protein is made in E. coli. TbpB has been expressed using a host leader.

[0036] Once protein has been obtained from the cells expressing the protein it is preferred to subject the crude product obtained to one or more purification processes. These processes may remove such contaminants as other proteins from the host cell, non-proteinaceous contaminants and also other components of the cell. The crude product can be purified by affinity chromatography, and preferably in the case of Tbps using a transferrin-bound affinity matrix. In this respect, reference to transferrin encompasses fragments, variants and derivatives of human transferrin that retain transferrin's binding to Tbps. A further aspect of the invention, described in more detail below, relates to recombinant transferrin, and the affinity matrix preferably comprises recombinant human transferrin.

[0037] A third aspect of the invention lies in a method of preparing a vaccine, comprising obtaining TbpA, TbpB or TbpA and TbpB according to the invention and combining said Tbp with a pharmaceutically acceptable carrier. The invention further provides use of a cell according to the invention in manufacture of Tbp, and use of a cell according to the invention in manufacture of a vaccine for protection against neisserial disease and/or meningococcal disease.

[0038] As described in examples below in more detail, transferrin binding proteins have been expressed recombinantly in E. coli. The invention is nevertheless of application to a range of host cell types, both prokaryotic and eukaryotic, such as yeast (eg. Saccharomyces cerevisiae, Pichia pastoris), insect cells (eg. baculovirus expression system), gram positive bacterial expression systems (eg. Bacillus subtilis) and mammalian cell culture. The expression vectors used in the invention have been designed for use in E. coli and corresponding vectors can be designed for use in other bacterial hosts, subject to selection of suitable promoters and origins of replication according to the host cell chosen. Examples of suitable cloning techniques and other hosts are described, for example, in Sambrook et al “Molecular Cloning: A laboratory Manual”, 1989.

[0039] The iron uptake proteins expressed according to the invention are derived from Neisseria. In the specific embodiments, transferrin binding proteins from pathogenic Neisseria, specifically N. meningitidis, have been expressed, more specifically of strain K454. Other neisserial transferrin binding proteins may suitably be expressed according to the invention, whether from virulent or a virulent strains and also from commensal strains. By reference to “iron uptake proteins” and “transferrin binding protein” it is intended to include whole, intact protein and also fragments and derivatives and variants thereof, provided that said fragments, derivatives and variants when administered in a vaccinating composition confer protection against subsequent challenge by meningococci and/or gonococci.

[0040] It is a significant advantage of the invention that it is now possible to produce iron uptake proteins and especially transferrin binding proteins in conformation suitable for vaccines and in useful quantities using the recombinant techniques of the invention.

[0041] A fourth aspect of the invention provides a method of purifying a Tbp-containing preparation, comprising eluting the preparation through an affinity matrix comprising immobilized transferrin.

[0042] A benefit of this method is that the affinity matrix will only bind functional transferrin binding protein, as only functional protein will bind to the immobilised transferrin. In this respect, reference to transferrin encompasses fragments, variants and derivatives of transferrin that retain transferrin's binding to Tbps. Thus, the eluate is both purified in respect of proteins that are not transferrin binding proteins and is also purified in that transferrin binding protein which is non-functional, mutated or otherwise does not bind transferrin passes through the matrix. It is preferred that human transferrin binding protein be immobilised, more preferably recombinant human transferrin binding protein, which confers a particular benefit in that the purified Tbp and hence preparation of a vaccine for human use is simplified as exclusive processes for removal of these contaminants can be avoided.

[0043] A further aspect of the invention provides an affinity matrix for purification of Tbps comprising human recombinant transferrin or a fragment thereof that binds to Tbp. The transferrin may be produced according to a method of the invention described below.

[0044] Typically, Tbp is expressed in a host cell and an extract of membrane-bound or membrane-associated Tbp obtained, such as using the mild extraction conditions described above. This extract, a crude Tbp-containing extract, is passed through the matrix, Tbp that can bind immobilized transferrin or fragment thereof is retained whilst non-functional Tbp and other contaminants pass through. The purified Tbp can then be separated from the matrix using conventional techniques, such as low pH.

[0045] A further composition of the invention contains a Tbp, wherein at least 90 percent by weight of said Tbp is active Tbp. The Tbp can be A or B, and by active is meant that the Tbp binds to transferrin. The composition is preferably free of Tbp that is not capable of binding transferrin.

[0046] For purification of Tbps, recombinant human transferrin can be obtained by:

[0047] A. obtaining a clone of human transferrin, or a fragment or derivative thereof;

[0048] B. inserting said clone, or fragment or derivative thereof, into an expression vector;

[0049] C. expressing the vector in a suitable host organism; and

[0050] D. isolating the expressed gene product from said host organism.

[0051] The clone can be isolated via a PCR based method, and the expression vector can be selected from the group consisting of pMTL and pET. The host organism is typically a bacterium, suitably E. coli, and specific embodiments of the invention use a host selected from the group consisting of Novablue DE3; HMS 174 DE3; BL21 DE3; JM 109; RV 308; and XL1 Blue.

[0052] The invention is now described in specific embodiments, illustrated by the accompanying drawings in which:—

[0053]FIG. 1 shows analysis of purified rTbps by SDS-PAGE (10%) under different denaturing conditions;

[0054]FIG. 2 shows purified rTbps electrophoretically transferred to nitrocellulose membrane and probed with antibodies raised against native Tbps and hTf-HRP conjugate;

[0055]FIG. 3 shows protection against IP challenge with N. meningitidis strain K454 conferred by rTbpA and rTbpB; and

[0056]FIG. 4 shows flow cytometry analysis indicating the surface location of expressed Tbps.

[0057] In more detail, for FIG. 1, a 10% SDS-PAGE gel of rTbps was stained with Gelcode blue. M is Pharmacia low range molecular weight markers, H is rTbp boiled at 100 degrees C. for 5 minutes before loading onto the gel, UH is rTbp not heated before loading onto the gel. For FIG. 2, rTbps were run on 10% SDS-PAGE gels and Western blotted onto nitrocellulose membrane. M is Biorad prestained molecular weight markers. A consistent pattern of degradation products is seen for batches of rTbpA and rTbpB when probed with serum to the native protein. For rTbpA the same pattern of bands is also seen when human transferrin HRP is used to probe the membrane. In FIG. 3, the number of survivors per group of 20 mice is shown against days from intraperitoneal challenge by N. meningitidis strain K454. The challenge dose for the upper panel was 5×10⁶ and for the lower was 5×10^(7.) In FIG. 4, surface labelling of E. coli JM109 with HTf-FITC is illustrated as counts shown against FITC.

EXAMPLE 1

[0058] tbp Gene Cloning and Expression

[0059] Primers to amplify N. meningitidis strain K454 (B15:P1.7, 16) tbps were designed using information from other sequenced N. meningitidis tbp genes in the Genbank database (and subsequent sequencing of the N and C termini of each tbp gene). 5′ primers engineered an NdeI (CATATG) site at the ATG start codon, and 3′ primers contained a BamHI (tbpA) or EcoRI (tbpB) site after the stop codon. 5′tbpA TTAGGGAAACCATATGCAACAGCAAC 3′tbpA GACGGATCCGCGTTTGGACGTTTAAAACTTC 5′tbpB GAATTGGATTTCATATGAACAATCC 3′tbpB GACGAATTCCGGCAGCCGTGCTTATCGC

[0060] Restriction Sites in Bold.

[0061] tbpB was further modified by replacing the native TbpB leader peptide coding sequence with that of the E. coli RlpB lipoprotein. Genes were cloned into pET22b (Novagen) initially, on an NdeI-BamHI (tbpA) or NdeI-EcoRI (rlpB::tbpB fragment and both strands of each clone sequenced to confirm gene integrity. These same fragments were subsequently subcloned into various pMTL vectors from which optimum expression was found in pMTL2010 (incorporating a lac UV5 promoter driving expression and a tetracycline resistance gene). Plasmid constructs were used to transform a variety of DE3 lysogens for pET22b directed expression (E. coli Novablue DE3, HMS 174 DE3 and BL21 DE3). pMTL2010 clones were used to transform E. coli JM109 and RV308 strains for expression.

[0062] We succeeded in expressing TbpA from all vectors, except from pMTL1015 and 2015 under the control of the mdh promoter which is stronger than the lac UV5 promoter. This suggests that strong gene expression causes toxicity. However, the rate of transcription in the pET expression system is greater than would be expected using mdh promoter driven expression, but no studies have been done to address this question. tbpA expressed better in BL21 DE3 than Novablue DE3 when cloned into pET vectors.

[0063] Replacement of the native neisserial TbpA leader sequence with that of CPG2 and PeIB leaders still gave rise to active protein (in terms of hTf binding) but offered no improvement over the native neisserial leader.

[0064] Sequence data for N. meningitidis strain K454 tbpA are shown below.

[0065] Production of Recombinant Meningococcal Tbps in E. coli

[0066] 1. Growth of Recombinant E. coli Strains

[0067] Recombinant E. coli strains (JM109 containing CAMR pMTL vectors with either tbpA or tbpB gene inserted) were grown up in 8 litre fermenters. Soytone-based production medium containing the appropriate antibiotic (either 1.25 mg/l tetracycline or 100 mg/l ampicillin) was used (see table 1). The fermenters were maintained at a temperature of 37° C. with an air flow of 0.5 vessel volumes per minute and a pH of 6.8-7. The dissolved oxygen tension was maintained at >40% by agitation. The cultures were allowed to grow until an A 600 nm of approximately 10 was reached, at which point Tbp expression was induced by the addition of IPTG to a final concentration of 1.0 mM. Cultures were then allowed to grow for a further 6-8 hours. Cells were harvested by centrifugation and the wet weight was determined. Table 1 Components of Soytone Based medium Medium Ingredient Amount (g/l) Bacto Soytone 40 K₂HPO₄ 4 KH₂PO₄ 1 NH₄Cl 1 CaCl₂.2H₂O 0.01 K₂SO₄ 2.6 Yeast extract 3 Glycerol 41 Trace elements 5 ml 1M MgCl₂.6H₂O 1 ml Mazu DF8005 O.1 ml Ampicillin/Tetracycline 100 mg/1.25 mg

[0068] 2. Preparation of Whole Cell Suspension

[0069] Recombinant E. coli cells harvested from fermenters were resuspended in 100 mM Tris-HCl buffer, pH 8.0, containing 0.5M NaCl. Cells were resuspended at 10% (w/v) and a hand held glass homogeniser was used to obtain an even suspension. For a typical experiment 40 g of cells were used and resuspended in 400 ml of buffer.

[0070] Two methods were used to obtain soluble recombinant transferrin binding proteins (rTbps) for affinity purification from the above cell suspension.

[0071] 3. Extraction of Tbps

[0072] 3.1 Procedure A. Direct Extraction From Whole Cells

[0073] An equal volume of 100 mM Tris-HCL buffer, pH 8.0, containing 0.5M NaCl and 4% (v/v) Elugent™ detergent (Calbiochem) was added to the whole cells and mixed thoroughly.

[0074] The suspension was incubated with gentle stirring at 4° C. for 16 h and then centrifuged at 39000 g for 40 min to remove bacterial debris. The supernatant containing soluble rTbps was gently decanted off in preparation for affinity chromatography.

[0075] 3.2 Procedure B. Extraction From Membrane Preparations

[0076] Crude membranes were prepared by disrupting cells with a bead-beater (Biospec Products, OK, US.). The cell suspension was transferred to a vessel half filled with 0.25-0.5 mm diameter glass beads. The vessel was sealed and placed on to the bead-beating apparatus. The suspension was beaten for 15 seconds to disrupt the cells. Once the beads had settled the suspension was decanted off and centrifuged at 8000 g for 30 min. The supernatant was discarded and the pellet containing crude membranes was resuspended in the original volume of 100 mM Tris-HCl buffer, pH 8.0, containing 0.5M NaCl. Once an even suspension was obtained an equal volume of Tris-HCl buffer, pH 8.0, containing 0.5M NaCl and 4% (v/v) Elugent™ detergent was added. The suspension was incubated with gentle stirring at 4° C. for 16 h. The suspension was then centrifuged at 39000 g for 40 min and the supernatant containing soluble rTbps was decanted off in preparation for affinity chromatography.

[0077] 4. Preparation of Transferrin-Sepharose Affinity Matrix

[0078] Transferrin-Sepharose affinity matrix was prepared using cyanogen bromide (CNBr) activated Sepharose 4B (Pharmacia Biotech) and human transferrin (Sigma). Transferrin purified from human blood will eventually be replaced with recombinant transferrin produced in E. coli. 15 g of CNBR activated Sepharose was suspended in 200 ml of 1 mM HCl and was washed for 15 min with another 2 l of the same solution on a sintered glass filter. 0.369 of human transferrin were dissolved in 50 ml coupling buffer (0.1 M NaHCO₃, pH 8.3, containing 0.5M NaCl) and mixed with the washed Sepharose 4B. The mixture was incubated overnight at 4° C. with gentle mixing. Excess uncoupled transferrin was then washed away with 250 ml of coupling buffer and remaining active groups were blocked by incubating with 0.1 M Tris-HCl buffer, pH 8.0, for 2 h. The transferrin-Sepharose was then washed with 3 cycles of low and high pH buffer using 250 ml of buffer for each wash. The low pH buffer was 0.1M acetate, pH 4.0, and the high pH buffer was 0.1M Tris-HCl, pH 8. Both contained 0.5M NaCl. The transferrin-Sepharose was stored at 4° C. in Tris-HCl, pH 8, until use.

[0079] 5. Affinity Chromatography

[0080] Supernatants containing rTbp A or rTbpB were loaded on to a 10 ml column of human transferrin linked to Sepharose 4B at a flow rate of 1 m/min. For rTbpB the column was saturated with iron by passing 200 ml of iron saturation buffer (40 mM Tris, 2 mM NaHCO₃, 25 mM Na citrate and 1 mM FeSO₄₀.7H₂O) through the column. For rTbpA this step was not necessary. The column was then washed with 20 column volumes of 100 mM Tris-HCl buffer, pH 8.0, containing 0.5M NaCl to remove unbound material. rTbps were eluted from the column using 50 mM glycine buffer, pH 2.0, containing 0.5M NaCI and 0.5-2% (v/v) Elugent™ detergent. Fractions containing rTbps were roughly located by monitoring the absorbance at 280 nm. As the ElugentM also absorbs at 280 nm, the presence of rTbps in selected fractions was confirmed by human transferrin-HRP (hTf-HRP) ligand blot and SDS-PAGE analysis. Fractions containing rTbps were pooled and applied to a HiPrep Desalting column (Sephadex G-25, Pharmacia) to partially remove glycine and free Elugen™. The protein concentration was then determined using the BCA kit (Pierce) using bovine serum albumin as the standard.

[0081] 6. Transferrin-HRP Ligand Blot

[0082] Transferrin-HRP ligand blot was carried out to accurately locate the presence of rTbps in eluted fractions and confirmed that active protein was being recovered.

[0083] A series of eight two-fold dilutions was prepared using a 50 ul sample of each selected fraction and 5 ul of each spotted onto nitrocellulose membrane. The membrane was blocked with PBS containing 0.05% Tween 20 (PBST) and 1% (w/v) dried skimmed milk powder for 1 hour. After washing in PBST for 3×10 min the membrane was incubated in hTf-HRP conjugate (Jackson Immunoresearch Laboratories) diluted to 1 ug/ml in PBST for 2 h. After further washing, as above, the membrane was developed in 4-chloronaphthol substrate.

[0084] 7. Results

[0085] 7.1 Yields of Tbps

[0086] A range of detergents was investigated and compared to Elugent for their ability to solubilise and stabilise the rTbps. Of the nine examined octyl glucopyranoside and dodecyl maltoside were the most suitable alternatives for use.

[0087] The yields of rTbps from E. coli JM109 clones containing CAMR pMTL expression vectors were as follows:— wet weight protein/litre Vector cells/litre rTbp/g cells culture (pMTL) culture (g) (ug/g) (mg) rTbpA 2000 19 306 5.8 2003  52* 252 ND 2010 23 350 8.0 2010 22 537 11.8 (no tet) rTbpB 2000 33 880 29.0 2003 29 238 6.9 2010 42 690 28.9 2010 35 890 31.1 (no tet)

[0088] Samples of E. coli JM109 clones expressing, respectively, tbpA and tbpB were deposited at ECACC on Jan. 24, 2000 under accession numbers 00012404 and 00012405, respectively.

[0089] Yields were estimated from 40 g samples of cells taken from paste grown in 2× soytone medium in 8 litre fermenters. Tbps were extracted at 4° C. using procedure A and purified on a transferrin-Sepharose column. Protein concentrations were estimated using the BCA assay. Vectors pMTL2000 and pMTL2003 have the ampicillin resistance marker and vector pMTL2010 has the tetracycline resistance marker. Values in the last row for each Tbp with pMTL2010 are for no antibiotic present in the medium.

[0090] 7.2 Characterisation of rTbps

[0091] 7.2.1 SDS-PAGE Analysis of Purified rTbps

[0092] Purified rTbps were analysed by SDS-PAGE (10%) under different denaturing conditions (FIG. 1). Full length rTbpA had a MW of approximately 100 kDa and constituted >90% of total protein as determined by densitometry of the coomassie stained gel. When not heated before SDS-PAGE two major bands of slightly lower MW were apparent which may represent membrane inserted and unprocessed forms of rTbpA. Full length rTbpB had a MW of approximately 85 kDa and constituted ˜80% of total protein as determined by densitometry. There was no difference in the SDS-PAGE profile of the heated and unheated protein.

[0093] 7.2.2 Western Blot of rTbps

[0094] After SDS-PAGE, purified rTbps were transferred electrophoretically to nitrocellulose membrane and probed with antibodies raised against native Tbps or hTf-HRP conjugate (FIG. 2). Like the native proteins purified from N. meningitidis, rTbpB binds hTf-HRP after SDS-PAGE and Western blot whereas rTbpA does not. A consistent pattern of low MW bands is seen for both rTbpA and rTbpB. These appear immediately after induction and when strains are grown at low temperatures and are most likely the result of in vivo proteolytic degradation of the full length rTbps. If they can be characterised and quantified they may not need to be removed from a vaccine preparation and may indeed contribute to protection afforded by the recombinant proteins.

[0095] 7.3 Protection Provided by Recombinant Tbps Against Meningococcal Challenge in Mice.

[0096] Harlan-NIH mice were immunised on days 0, 21 and 28 with lOpg per dose of rTbpA, r rTbp or rTbpA+rTbpB in Freund's adjuvant. Mice were then given an intraperitoneal challenge of N. meningitidis strain K454 containing 10 mg of iron-saturated human transferrin on day 35. A further dose of human transferrin is given by intraperitoneal injection after 24 h. The numbers of surviving mice are then recorded for 4 days.

[0097]Neisseria meningiditis Strain K454 tbpA Gene DNA Sequence ATGCAACAGCAACATTTGTTCCGATTCAATATTTTATGCC 40 TGTCTTTAATGACTGCGCTGCCCGCTTATGCAGAAAATGT 80 GCAAGCCGGACAAGCACAGGAAAAACAGTTGGATACCATA 120 CAGGTAAAAGCCAAAAAACAGAAAACCCGCCGCGATAACG 160 AAGTAACCGGGCTGGGCAAGTTGGTCAAGTCTTCCGATAC 200 GCTAAGTAAAGAACAGGTTTTGAATATCCGAGACCTGACC 240 CGTTATGATCCGGGTATTGCCGTGGTCGAACAGGGTCGGG 280 GCGCAAGTTCCGGCTATTCAATACGCGGCATGGATAAAAA 320 CCGCGTTTCCTTAACGGTGGACGGCGTTTCGCAAATACAG 360 TCCTACACCGCGCAGGCGGCATTGGGCGGGACGAGGACGG 400 CGGGCAGCAGCGGCGCAATCAATGAAATCGAGTATGAAAA 440 CGTCAAAGCTGTCGAAATCAGCAAAGGCTCAAACTCGGTC 480 GAACAAGGCAGCGGCGCATTGGCGGGCTCGGTCGCATTTC 520 AAACCAAAACCGCCGACGATGTTATCGGGGAAGGCAGGCA 560 GTGGGGCATTCAGAGTAAAACCGCCTATTCCGGCAAAAAC 600 CGGGGGCTTACCCAATCCATCGCGCTGGCGGGGCGCATCG 640 GCGGTGCGGAGGCTTTGCTGATCCACACCGGGCGGCGCGC 680 GGGGGAAATCCGCGCCCACGAAGATGCAGGACGCGGCGTT 720 CAGAGCTTTAACAGGCTGGTGCCGGTTGAAGACAGCAGCA 760 ATTACGCCTATTTCATCGTTAAAGAAGAATGCAAAAACGG 800 GAGTTATGAAACGTGTAAAGCGAATCCCAAAAAAGATGTT 840 GTCGGCAAAGACGAACGTCAAACGGTTTCCACCCGAGACT 880 ACACGGGTCCCAACCGCTTCCTCGCCGATCCGCTTTCATA 920 CGAAAGCCGGTCGTGGCTGTTCCGCCCGGGTTTTCGTTTT 960 GAGAATAAGCGGCACTACATCGGCGGCATACTCGAACACA 1000 CGCAACAAACTTTCGACACGCGCGATATGACGGTTCCGGC 1040 ATTCCTGACCAAGGCGGTTTTTGATGCAAATAAAAAACAG 1080 GCGGGTTCTTTGCCCGGTAACGGCAAATACGCGGGCAACC 1120 ACAAATACGGCGGACTGTTTACCAACGGCGAAAACGGTGC 1160 GCTGGTGGGCGCGGAATACGGTACGGGCGTGTTTTACGAC 1200 GAGACGCACACCAAAAGCCGCTACGGTTTGGAATATGTCT 1240 ATACCAATGCCGATAAAGACACTTGGGCGGATTATGCCCG 1280 CCTCTCTTACGACCGGCAGGGCGTCGGTTTGGATAATCAT 1320 TTTCAGCAGACGCACTGTTCTGCCGACGGTTCGGACAAAT 1360 ATTGCCGCCCGAGTGCCGACAAGCCGTTTTCCTATTACAA 1400 ATCCGATCGCGTGATTTACGGGGAAAGCCACAGGCTCTTG 1440 CAGGCGGCATTCAAAAAATCCTTCGATACCGCCAAAATCC 1480 GCCACAACCTGAGCGTGAATCTCGGGTTTGACCGCTTTGG 1520 CTCTAATCTCCGCCATCAGGATTATTATTATCAACATGCC 1560 AACCGCGCCTATTCGTCGAACACGCCCCCTCAAAACAACG 1600 GCAAAAAAATCAGCCCCAACGGCAGTGAAACCAGCCCCTA 1640 TTGGGTCACCATAGGCAGGGGAAATGTCGTTACGGGGCAA 1680 ATCTGCCGCTTGGGCAACAATACTTATACGGACTGCACGC 1720 CGCGCAGCATCAACGGTAAAAGCTATTACGCGGCAGTTCG 1760 GGACAATGTCCGTTTGGGCAGGTGGGCGGATGTCGGCGCG 1800 GGCTTGCGCTACGACTACCGCAGCACGCATTCGGACGACG 1840 GGAGCGTTTCCACCGGCACGCACCGCACCTTGTCCTGGAA 1880 CGCCGGCATCGTCCTCAAACCTACCGACTGGCTGGATTTG 1920 ACTTACCGCACCTCAACCGGCTTCCGCCTGCCCTCGTTTG 1960 CGGAAATGTACGGCTGGCGGGCGGGTGTTCAAAGCAAGGC 2000 GGTCAAAATCGATCCGGAAAAATCGTTCAACAAAGAAGCC 2040 GGCATCGTGTTTAAAGGCGATTTCGGCAACTTGGAGGCAA 2080 GTTGGTTCAACAATGCCTACCGCGATTTGATTGTCCGGGG 2120 TTATGAAGCGCAAATTAAAGACGGCAAAGAAGAAGCCAAA 2160 GGCGACCCGGCTTACCTCAATGCCCAAAGCGCGCGGATTA 2200 CCGGCATCAATATTTTGGGCAAAATCGATTGGAACGGCGT 2240 ATGGGATAAATTGCCCGAAGGTTGGTATTCTACATTTGCC 2280 TATAATCGTGTCCGTGTCCGCGACATCAAAAAACGCGCAG 2320 ACCGCACCGATATTCAATCACATCTGTTTGATGCCATCCA 2360 ACCCTCGCGCTATGTCGTCGGCTTGGGCTATGACCAACCG 2400 GAAGGCAAATGGGGTGTGAACGGTATGCTGACTTATTCCA 2440 AAGCCAAGGAAATCACAGAGTTGTTGGGCAGCCGGGCTTT 2480 GCTCAACGGCAACAGCCGCAATACAAAAGCCACCGCGCGC 2520 CGTACCCGCCCTTGGTATATTGTGGACGTGTCCGGTTATT 2560 ACACGGTTAAAAAACACTTTACCCTCCGTGCGGGCGTGTA 2600 CAACCTCCTCAACTACCGCTATGTTACTTGGGAAAATGTG 2640 CGGCAAACTGCCGGCGGCGCAGTCAACCAACACAAAAATG 2680 TCGGCGTTTACAACCGATATGCCGCCCCCGGTCGCAACTA 2720 CACATTTAGCTTGGAAATGAAGTTTTAA 2748

[0098] Translation of the Neisseria meningiditis Strain K454 tbpA Gene DNA Sequence MQQQHLFRFNILCLSLMTALPAYAENVQAGQAQEKQLDTI 40 QVKAKKQKTRRDNEVTGLGKLVKSSDTLSKEQVLNIRDLT 80 RYDPGIAVVEQGRGASSGYSIRGMDKNRVSLTVDGVSQIQ 120 SYTAQAALGGTRTAGSSGAINEIEYENVKAVETSKGSNSV 160 EQGSGALAGSVAFQTKTADDVIGEGRQWGIQSKTAYSGKN 200 RGLTQSIALAGRIGGAEALLIHTGRRAGEIRAHEDAGRGV 240 QSFNRLVPVEDSSNYAYFIVKEECKNGSYETCKANPKKDV 280 VGKDERQTVSTRDYTGPNRFLADPLSYESRSWLFRPGFRF 320 ENKRHYIGGILEHTQQTFDTRDMTVPAFLTKAVFDANKKQ 360 AGSLPGNGKYAGNHKYGGLFTNGENGALVGAEYGTGVFYD 400 ETHTKSRYGLEYVYTNADKDTWADYARLSYDRQGVGLDNH 440 FQQTHCSADGSDKYCRPSADKPFSYYKSDRVIYGESHRLL 480 QAAFKKSFDTAKIRHNLSVNLGFDRFGSNLRHQDYYYQHA 520 NRAYSSNTPPQNNGKKISPNGSETSPYWVTIGRGNVVTGQ 560 ICRLGNNTYTDCTPRSINGKSYYAAVRDNVRLGRWADVGA 600 GLRYDYRSTHSDDGSVSTGTHRTLSWNAGIVLKPTDWLDL 640 TYRTSTGFRLPSFAEMYGWRAGVQSKAVKIDPEKSFNKEA 680 GIVFKGDFGNLEASWFNNAYRDLIVRGYEAQIKDGKEEAK 720 GDPAYLNAQSARITGINILGKIDWNGVWDKLPEGWYSTFA 760 YNRVRVRDIKKRADRTDIQSHLFDAIQPSRYVVGLGYDQP 800 EGKWGVNGMLTYSKAKEITELLGSRALLNGNSRNTKATAR 840 RTRPWYIVDVSGYYTVKKHFTLRAGVYNLLNYRYVTWENV 880 RQTAGGAVNQHKNVGVYNRYAAPGRNYTFSLEMKF 915

[0099] Molecular Weight 102091.85 Daltons   915 Amino Acids   124 Strongly Basic(+) Amino Acids (K, R)    93 Strongly Acidic(−) Amino Acids (D, E)   274 Hydrophobic Amino Acids (A, I, L, F, W, V)   282 Polar Amino Acids (N, C, Q, S, T, Y)  9.472 Isoelectric Point 33.723 Charge at pH 7.0 Total number of bases translated is 2748 % A = 2635  [724] % G = 26.67  [733] % T = 20.23  [556] % C = 26.75  [735] % Ambiguous = 0.00   [0] % A + T = 46.58 [1280] % C + G = 53.42 [1468]

[0100]Neisseria meningiditis Strain K454 tbpB Gene DNA Sequence ATGAACAATCCATTGGTGAATCAGGCTGCTATGGTGCTGC 40 CTGTGTTTTTGTTGAGTGCTTGTTTGGGCGGAGGCGGCAG 80 TTTCGATCTTGATTCTGTCGATACCGAAGCCCCGCGTCCC 120 GCGCCAAAATATCAAGATGTTTTTTCCGAAAAACCGCAAG 160 CCCAAAAAGACCAAGGCGGATACGGTTTTGCAATGAGGTT 200 GAAACGGAGGAATTGGTATCCGCAGGCAAAAGAAGACGAG 240 GTTAAACTGGACGAGAGTGATTGGGAGGCGACAGGATTGC 280 CGGACGAACCTAAGGAACTCCCTAAACGGCAAAAATCGGT 320 TATCGAAAAAGTAGAAACAGACAGCGACAACAATATTTAT 360 TCTTCCCCCTATCTCAAACCATCAAACCATCAAAACGGCA 400 ACACTGGCAACGGTATAAACCAACCTAAAAATCAGGCAAA 440 AGATTACGAAAATTTTAAATATGTTTATTCCGGCTGGTTT 480 TACAAACACGCCAAACGAGAGTTTAACTTAAAGGTGGAAC 520 CTAAAAGTGCAAAAAACGGCGACGACGGTTATATCTTCTA 560 TCACGGTAAAGAACCTTCCCGACAACTTCCCGCTTCTGGA 600 AAAATTACCTATAAAGGTGTGTGGCATTTTGCGACCGATA 640 CAAAAAAGGGTCAAAAATTTCGTGAAATTATCCAACCTTC 680 AAAAAGTCAAGGCGACAGGTATAGCGGATTTTCGGGCGAT 720 GACGGCGAAGAATATTCCAACAAAAACAAATCCACGCTGA 760 CAGATGGTCAAGAGGGTTATGGTTTTACCTCAAATTTAGA 800 AGTGGATTTCCATAATAAAAAATTGACGGGCAAACTGATA 840 CGCAACAATGCGAATACCGATAACAACCAAGCCACCACCA 880 CGCAATACTACAGCCTTGAGGCTCAAGTAACAGGCAACCG 920 CTTCAACGGCAAGGCAACGGCAACCGACAAACCCCAACAA 960 AACAGCGAAACCAAGGAACATCCCTTTGTTTCCGATTCGT 1000 CTTCTTTGAGCGGCGGCTTTTTCGGCCCGCAGGGTGAGGA 1040 ATTGGGTTTCCGCTTTTTGAGCGACGATCAAAAAGTTGCC 1080 GTTGTCGGCAGCGCGAAAACCAAAGACAAACCCGCAAATG 1120 GCAATACTGCGGCGGCTTCAGGCGGCACAGATGCGGCAGC 1160 ATCAAACGGTGCGGCAGGCACGTCGTCTGAAAACGGTAAG 1200 CTGACCACGGTTTTGGATGCGGTCGAGCTGAAATTGGGCG 1240 ATAAGAAAGTCCAAAAGCTCGACAACTTCAGCAACGCCGC 1280 CCAACTGGTTGTCGACGGCATTATGATTCCGCTCTTGCCC 1320 GAGGCTTCCGAAAGTGGGAACAATCAAGCCAATCAAGGTA 1360 CAAATGGCGGAACAGCCTTTACCCGCAAATTTGACCACAC 1400 GCCGGAAAGTGATAAAAAAGACGCCCAAGCAGGTACGCAG 1440 ACGAATGGGGCGCAAACCGCTTCAAATACGGCAGGTGATA 1480 CCAATGGCAAAACAAAAACCTATGAAGTCGAAGTCTGCTG 1520 TTCCAACCTCAATTATCTGAAATACGGAATGTTGACGCGC 1560 AAAAACAGCAAGTCCGCGATGCAGGCAGGAGAAAGCAGTA 1600 GTCAAGCTGATGCTAAAACGGAACAAGTTGAACAAAGTAT 1640 GTTCCTCCAAGGCGAGCGCACCGATGAAAAAGAGATTCCA 1680 AGCGAGCAAAACATCGTTTATCGGGGGTCTTGGTACGGAT 1720 ATATTGCCAACGACAAAAGCACAAGCTGGAGCGGCAATCC 1760 TTCCAATGCAACGAGTGGCAACAGGGCGGAATTTACTGTG 1800 AATTTTGCCGATAAAAAAATTACTGGTACGTTAACCGCTG 1840 ACAACAGGCAGGAGGCAACCTTTACCATTGATGGTAATAT 1880 TAAGGACAACGGCTTTGAAGGTACGGCGAAAACTGCTGAG 1920 TCAGGTTTTGATCTCGATCAAAGCAATACCACCCGCACGC 1960 CTAAGGCATATATCACAGATGCCAAGGTGCAGGGCGGTTT 2000 TTACGGGCCCAAAGCCGAAGACTTGGGCGGATGGTTTGCC 2040 TATCCGGGCGATAAACAAACGAAAAATGCAACAAATGCAT 2080 CCGGCAATAGCAGTGCAACTGTCGTATTCGGTGCGAAACG 2120 CCAACAGCCTGTGCAATAA 2139

[0101] Translation of the Neisseria meningiditis Strain K454 tbpB Gene DNA Sequence MNNPLVNQAAMVLPVFLLSACLGGGGSFDLDSVDTEAPRP 40 APKYQDVFSEKPQAQKDQGGYGFAMRLKRRNWYPQAKEDE 80 VKLDESDWEATGLPDEPKELPKRQKSVIEKVETDSDNNIY 120 SSPYLKPSNHQNGNTGNGINQPKNQAKDYENFKYVYSGWF 160 YKHAKREFNLKVEPKSAKNGDDGYIFYHGKEPSRQLPASG 200 KITYKGVWHFATDTKKGQKFREIIQPSKSQGDRYSGFSGD 240 DGEEYSNKNKSTLTDGQEGYGFTSNLEVDFHNKKLTGKLI 280 RNNANTDNNQATTTQYYSLEAQVTGNRFNGKATATDKPQQ 320 NSETKEHPFVSDSSSLSGGFFGPQGEELGFRFLSDDQKVA 360 VVGSAKTKDKPANGNTAAASGGTDAAASNGAAGTSSENGK 400 LTTVLDAVELKLGDKKVQKLDNFSNAAQLVVDGIMIPLLP 440 EASESGNNQANQGTNGGTAFTRKFDHTPESDKKDAQAGTQ 480 TNGAQTASNTAGDTNGKTKTYEVEVCCSNLNYLKYGMLTR 520 KNSKSAMQAGESSSQADAKTEQVEQSMFLQGERTDEKEIP 560 SEQNIVYRGSWYGYIANDKSTSWSGNASNATSGNRAEFTV 600 NFADKKITGTLTADNRQEATFTIDGNIKDNGFEGTAKTAE 640 SGFDLDQSNTTRTPKAYITDAKVQGGFYGPKAEELGGWFA 680 YPGDKQTKNATNASGNSSATVVFGAKRQQPVQ 712

[0102] Molecular Weight 77386.47 Daltons     712 Amino Acids     84 Strongly Basic(+) Amino Acids (K, R)     90 Strongly Acidic(−) Amino Acids (D, E)     184 Hydrophobic Amino Acids (A, I, L, F, W, V)     241 Polar Amino Acids (N, C, Q, S, T, Y)   6.000 Isoelectric Point −4.964 Charge at PH 7.0 Total number of bases translated is 2139 % A = 32.54  [696] % G = 24.26  [519] % T = 20.20  [432] % C = 23.00  [492] % Ambiguous = 0.00   [0] % A + T = 52.73 [1128] % C + G = 47.27 [1011]

EXAMPLE 2

[0103] Recombinant Human Transferrin Expression in E. coli

[0104] As an alternative to using human blood derived transferrin for the purification of rTbps, we have expressed a recombinant form of human transferrin in E. coli. We have expressed individual lobes of the transferrin protein, along with full length protein.

[0105] Human transferrin was cloned by PCR amplification of an existing gene clone (cDNA sequence Funmei Yang et al., (1984) PNAS 81: 2752-2756). Before use, the internal NdeI sites present in the hTf gene were removed by mutagenic PCR, as follows:

[0106] 1. PCR amplification of the transferrin with the oligomers below removed the first NdeI site at amino acids 25-26, without changing the amino acid sequence. An NruI site is included in the 5′ primer, enabling the product to be cloned into a previously engineered version of hTf containing an NruI site just upstream of the NdeI site (also engineered without changing the amino acid sequence).

[0107] Primers for Removing 5′ (Upstream) NdeI Site 5′TTT CGC GAG GAG ATG AAA AGO GTC ATT OCA TCC 3′ (5′primer) 5′GTT CTA GAG TGG GAG CCC TAC CTC TGA G 3′ (3′primer)

[0108] 2. Removal of the second NdeI site was a two step process: firstly, a version of hTf was generated containing an appropriately placed PvuI site in it (amino acids 642-645). The PvuI site was introduced by PCR amplification of hTf lacking the upstream NdeI site (generated as detailed above) with the following oligomers

[0109] Primers for Introducing PvuI Site into hTf 5′CAT ATG GTC CCT GAT AAA ACT GTG AG 3′ (5′primer) 5′CGA TCG TGA AGT TTG GCC AAA CAT ACT G 3′ (3′primer)

[0110] Then the 3′ end of hTf was amplified using the following oligomers:

[0111] Primers for Removing 3′ (Downstream) NdeI Site 5′CGA TCG AAA CAG GTA TGA AAA ATA CTT AG 3′ (5′primer) 5′GTT CTA GAG TGG CAG CCC TAC CTC TGA G 3′ (3′primer)

[0112] 3. The PvuI sites were used to join the two products together, forming a full length recombinant hTf gene with a single NdeI site at the level of the start ATG codon.

[0113] The N terminal clone was prepared by PCR, using the oligomers below, generating an N terminus clone without the native leader sequence, encompassing amino acids 1-337 of the mature transferrin sequence.

[0114] N Terminus Clone Primers 5′CAT ATG GTC CCT GAT AAA ACT GTG AG 3′ (5′primer) 5′TCT AGA TTA ATC TGT TGG GGC TTC TGG GCA TG 3′ (3′primer)

[0115] The C terminal lobe was amplified using the oligomers below, which again enabled cloning into the NdeI site of pET and pMTL vectors, and encompassed amino acids 338-679 of the mature transferrin sequence.

[0116] C Terminus Clone Primers 5′CAT ATG GAA TGC AAG CCT GTG AAG TGG 3′ (5′primer) 5′GTT CTA GAG TGG CAG CCC TAC CTC TGA G 3′ (3′primer)

[0117] Full-length and hTf lobes were cloned into pET22b and pET26b, initially, on an NdeI-XbaI fragment.

[0118] Expression Studies

[0119] Expression studies were carried out by growing E. coli BL21 DE3 carrying the hTf pET22b and pET26b clones, to OD₆₀₀ 0.7-1.0. Expression was induced with 1 mM IPTG and hTf production monitored over the course of two hours by dot blot and Western blotting, using a goat anti-human transferrin polyclonal antibody (Sigma). The size of full length and C terminus recombinant matched that expected for unglycosylated human transferrin and its individual lobes. Microscope examination revealed that expression of hTf resulted in the production of inclusion bodies. This precipitated material requires solubilisation and refolding in order to generate functional material.

EXAMPLE 3

[0120] Recombinant Transferrin Refolding and Preparation of Affinity Column

[0121] The protocol for solubilisation and refolding is described in (Hoefkins P., et al. (1996) Int. J. Biochem. Cell. Biol. 28, 975-982. Briefly, the protocol is:—

[0122] 1. Isolate inclusion body material by standard cell lysis and centrifugation.

[0123] 2. Dissolve pelleted protein in 8M urea, 1 mM DTT, 40 mM Tris/HCl, 10% glycerol (v/v) pH 7.6.

[0124]3. Dilute dissolved protein in renaturation buffer (0.1 mM Na-EDTA, 0.1 mM Tris/HCl, 1.0 mM reduced glutathione (GSH), pH 8.2) to a concentration of 20 μg/ml.

[0125] 4. Incubate at 6° C. for 15 min.

[0126] 5. Add oxidised glutathione (GSSG) to a final concentration of 0.5 mM.

[0127] 6. Incubate for further 22 hr at 6° C.

[0128] 7. Concentrate and dialyse against 10 mM NaHCO₃.

[0129] 8. Saturate with iron and assess purity (where necessary, clean up using size exclusion chromatography or other chromatographic technique).

[0130] 9. Conjugate with Sepharose 4B (Amersham Pharmacia) to generate affinity matrix.

[0131] The resultant transferrin affinity column is used to purify recombinant Tbps from Example 1.

EXAMPLE 4

[0132] Protective Effect of Recombinant Tbps

[0133] Groups of 20 mice were inoculated with rTbpA, rTbpB, both rTbpA and rTbpB, or a control of no vaccine. Their survival was monitored following challenge by 5×10⁶ and 5×10⁷ N. meningitidis strain K454 and the results illustrated in FIG. 3.

[0134] rTbpA and rTbpB conferred protection against challenge, confirming antigenicity of native Tbp had been retained in the recombinant proteins. In more detail, both rTbpA and rTbpB provide strong protection against meningococcal challenge, with greater protection provided by TbpA at the higher challenge dose: Protection with TbpA has not been previously reported. The combination of TbpA+TbpB is also protective and may provide the most effective vaccine against a range of challenge strains.

EXAMPLE 5

[0135] Surface Expression of Recombinant Tbps

[0136]E. coli expressing recombinant Tbps are probed with fluorescently labelled human transferrin, with the results being shown in FIG. 4.

[0137] It is seen that the parent E. coli strain and the uninduced strains possessing the Tbp gene show little fluorescence. The induced E. coli peak is shifted to the right on the X-axis, indicating increased fluorescence caused by binding of the labelled human transferin to the bacteria, indicating location of the recombinant Tbps on the bacterial surface.

EXAMPLE 6

[0138] Cross-Reactivity of Antisera Raised Against rTbpA and rTbpB

[0139] Whole-cell ELISA studies are carried out using a range of patient isolates collected in Norway to assess the cross-reactivity of antisera raised against rTbpA and rTbpB with Tbps expressed by these isolates, with the results being shown in table 2. TABLE 2 Meningococcal whole-cell ELISA titers of sera from mice immunized with rTpbA and/or rTbpB Whole-cell ELISA titers^(c) in Meningococcal strain details immunization group: Serotype or group Isolate Source^(a) TbpB type^(b) TpbA TbpB B:15P1.7, 16  6 H 19,676 3,050 B:15:P1.7, 16  8 H 20,650 3,667 C:15P1.7, 16  9 H  4,987   614 C:15P1.7, 16 12 H  9,726 1,267 C:15:P1.7, 16 13 H  7,514 1,389 C:15:P1.7, 16 14 H  2,301   709 B:15:P1.2 20 H  3,893 1,283 B:15:P1.12V 22 H 16,364 3,488 B:15:P1.12V 23 H 11,903 1,858 C:2a:P1.2 29 H  7,785 3,269 B:NT:P1.12 32 H 17,385 10,226  B:NT:P1.16 33 H  9,614   339 B:4:P1.12 37 H 18,653 7,461 B:19:P1.15 39 H 18,108 1,609 C:2a:P1.2 26 L  2,539   216 C:2a:P1.2 27 L 12,116 1,314 C:2a:P1.2 28 L 172,779  1,130

[0140] It is seen that titers against isolates of a variety of different sera groups, sera types and serosubtypes were consistently higher for antisera raised against rTbpA than for antisera raised against rTbpB.

[0141] Three isolates expressing low-molecular mass TbpB and the rTbpB antiserum showed reaction with these cells. Pre-immune sera from these mice showed no reaction with the meningococcal isolates.

[0142] The invention thus provides recombinant expression of iron uptakes proteins and compositions, vaccines and uses based thereon.

1 18 1 26 DNA Artificial Sequence primer 1 ttagggaaac catatgcaac agcaac 26 2 31 DNA Artificial Sequence primer 2 gacggatccg cgtttggacg tttaaaactt c 31 3 25 DNA Artificial Sequence primer 3 gaattggatt tcatatgaac aatcc 25 4 28 DNA Artificial Sequence primer 4 gacgaattcc ggcagccgtg cttatcgc 28 5 2748 DNA Neisseria meningitidis 5 atgcaacagc aacatttgtt ccgattcaat attttatgcc tgtctttaat gactgcgctg 60 cccgcttatg cagaaaatgt gcaagccgga caagcacagg aaaaacagtt ggataccata 120 caggtaaaag ccaaaaaaca gaaaacccgc cgcgataacg aagtaaccgg gctgggcaag 180 ttggtcaagt cttccgatac gctaagtaaa gaacaggttt tgaatatccg agacctgacc 240 cgttatgatc cgggtattgc cgtggtcgaa cagggtcggg gcgcaagttc cggctattca 300 atacgcggca tggataaaaa ccgcgtttcc ttaacggtgg acggcgtttc gcaaatacag 360 tcctacaccg cgcaggcggc attgggcggg acgaggacgg cgggcagcag cggcgcaatc 420 aatgaaatcg agtatgaaaa cgtcaaagct gtcgaaatca gcaaaggctc aaactcggtc 480 gaacaaggca gcggcgcatt ggcgggctcg gtcgcatttc aaaccaaaac cgccgacgat 540 gttatcgggg aaggcaggca gtggggcatt cagagtaaaa ccgcctattc cggcaaaaac 600 cgggggctta cccaatccat cgcgctggcg gggcgcatcg gcggtgcgga ggctttgctg 660 atccacaccg ggcggcgcgc gggggaaatc cgcgcccacg aagatgcagg acgcggcgtt 720 cagagcttta acaggctggt gccggttgaa gacagcagca attacgccta tttcatcgtt 780 aaagaagaat gcaaaaacgg gagttatgaa acgtgtaaag cgaatccgaa aaaagatgtt 840 gtcggcaaag acgaacgtca aacggtttcc acccgagact acacgggtcc caaccgcttc 900 ctcgccgatc cgctttcata cgaaagccgg tcgtggctgt tccgcccggg ttttcgtttt 960 gagaataagc ggcactacat cggcggcata ctcgaacaca cgcaacaaac tttcgacacg 1020 cgcgatatga cggttccggc attcctgacc aaggcggttt ttgatgcaaa taaaaaacag 1080 gcgggttctt tgcccggtaa cggcaaatac gcgggcaacc acaaatacgg cggactgttt 1140 accaacggcg aaaacggtgc gctggtgggc gcggaatacg gtacgggcgt gttttacgac 1200 gagacgcaca ccaaaagccg ctacggtttg gaatatgtct ataccaatgc cgataaagac 1260 acttgggcgg attatgcccg cctctcttac gaccggcagg gcgtcggttt ggataatcat 1320 tttcagcaga cgcactgttc tgccgacggt tcggacaaat attgccgccc gagtgccgac 1380 aagccgtttt cctattacaa atccgatcgc gtgatttacg gggaaagcca caggctcttg 1440 caggcggcat tcaaaaaatc cttcgatacc gccaaaatcc gccacaacct gagcgtgaat 1500 ctcgggtttg accgctttgg ctctaatctc cgccatcagg attattatta tcaacatgcc 1560 aaccgcgcct attcgtcgaa cacgccccct caaaacaacg gcaaaaaaat cagccccaac 1620 ggcagtgaaa ccagccccta ttgggtcacc ataggcaggg gaaatgtcgt tacggggcaa 1680 atctgccgct tgggcaacaa tacttatacg gactgcacgc cgcgcagcat caacggtaaa 1740 agctattacg cggcagttcg ggacaatgtc cgtttgggca ggtgggcgga tgtcggcgcg 1800 ggcttgcgct acgactaccg cagcacgcat tcggacgacg gcagcgtttc caccggcacg 1860 caccgcacct tgtcctggaa cgccggcatc gtcctcaaac ctaccgactg gctggatttg 1920 acttaccgca cctcaaccgg cttccgcctg ccctcgtttg cggaaatgta cggctggcgg 1980 gcgggtgttc aaagcaaggc ggtcaaaatc gatccggaaa aatcgttcaa caaagaagcc 2040 ggcatcgtgt ttaaaggcga tttcggcaac ttggaggcaa gttggttcaa caatgcctac 2100 cgcgatttga ttgtccgggg ttatgaagcg caaattaaag acggcaaaga agaagccaaa 2160 ggcgacccgg cttacctcaa tgcccaaagc gcgcggatta ccggcatcaa tattttgggc 2220 aaaatcgatt ggaacggcgt atgggataaa ttgcccgaag gttggtattc tacatttgcc 2280 tataatcgtg tccgtgtccg cgacatcaaa aaacgcgcag accgcaccga tattcaatca 2340 catctgtttg atgccatcca accctcgcgc tatgtcgtcg gcttgggcta tgaccaaccg 2400 gaaggcaaat ggggtgtgaa cggtatgctg acttattcca aagccaagga aatcacagag 2460 ttgttgggca gccgggcttt gctcaacggc aacagccgca atacaaaagc caccgcgcgc 2520 cgtacccgcc cttggtatat tgtggacgtg tccggttatt acacggttaa aaaacacttt 2580 accctccgtg cgggcgtgta caacctcctc aactaccgct atgttacttg ggaaaatgtg 2640 cggcaaactg ccggcggcgc agtcaaccaa cacaaaaatg tcggcgttta caaccgatat 2700 gccgcccccg gtcgcaacta cacatttagc ttggaaatga agttttaa 2748 6 915 PRT Neisseria meningitidis 6 Met Gln Gln Gln His Leu Phe Arg Phe Asn Ile Leu Cys Leu Ser Leu 1 5 10 15 Met Thr Ala Leu Pro Ala Tyr Ala Glu Asn Val Gln Ala Gly Gln Ala 20 25 30 Gln Glu Lys Gln Leu Asp Thr Ile Gln Val Lys Ala Lys Lys Gln Lys 35 40 45 Thr Arg Arg Asp Asn Glu Val Thr Gly Leu Gly Lys Leu Val Lys Ser 50 55 60 Ser Asp Thr Leu Ser Lys Glu Gln Val Leu Asn Ile Arg Asp Leu Thr 65 70 75 80 Arg Tyr Asp Pro Gly Ile Ala Val Val Glu Gln Gly Arg Gly Ala Ser 85 90 95 Ser Gly Tyr Ser Ile Arg Gly Met Asp Lys Asn Arg Val Ser Leu Thr 100 105 110 Val Asp Gly Val Ser Gln Ile Gln Ser Tyr Thr Ala Gln Ala Ala Leu 115 120 125 Gly Gly Thr Arg Thr Ala Gly Ser Ser Gly Ala Ile Asn Glu Ile Glu 130 135 140 Tyr Glu Asn Val Lys Ala Val Glu Ile Ser Lys Gly Ser Asn Ser Val 145 150 155 160 Glu Gln Gly Ser Gly Ala Leu Ala Gly Ser Val Ala Phe Gln Thr Lys 165 170 175 Thr Ala Asp Asp Val Ile Gly Glu Gly Arg Gln Trp Gly Ile Gln Ser 180 185 190 Lys Thr Ala Tyr Ser Gly Lys Asn Arg Gly Leu Thr Gln Ser Ile Ala 195 200 205 Leu Ala Gly Arg Ile Gly Gly Ala Glu Ala Leu Leu Ile His Thr Gly 210 215 220 Arg Arg Ala Gly Glu Ile Arg Ala His Glu Asp Ala Gly Arg Gly Val 225 230 235 240 Gln Ser Phe Asn Arg Leu Val Pro Val Glu Asp Ser Ser Asn Tyr Ala 245 250 255 Tyr Phe Ile Val Lys Glu Glu Cys Lys Asn Gly Ser Tyr Glu Thr Cys 260 265 270 Lys Ala Asn Pro Lys Lys Asp Val Val Gly Lys Asp Glu Arg Gln Thr 275 280 285 Val Ser Thr Arg Asp Tyr Thr Gly Pro Asn Arg Phe Leu Ala Asp Pro 290 295 300 Leu Ser Tyr Glu Ser Arg Ser Trp Leu Phe Arg Pro Gly Phe Arg Phe 305 310 315 320 Glu Asn Lys Arg His Tyr Ile Gly Gly Ile Leu Glu His Thr Gln Gln 325 330 335 Thr Phe Asp Thr Arg Asp Met Thr Val Pro Ala Phe Leu Thr Lys Ala 340 345 350 Val Phe Asp Ala Asn Lys Lys Gln Ala Gly Ser Leu Pro Gly Asn Gly 355 360 365 Lys Tyr Ala Gly Asn His Lys Tyr Gly Gly Leu Phe Thr Asn Gly Glu 370 375 380 Asn Gly Ala Leu Val Gly Ala Glu Tyr Gly Thr Gly Val Phe Tyr Asp 385 390 395 400 Glu Thr His Thr Lys Ser Arg Tyr Gly Leu Glu Tyr Val Tyr Thr Asn 405 410 415 Ala Asp Lys Asp Thr Trp Ala Asp Tyr Ala Arg Leu Ser Tyr Asp Arg 420 425 430 Gln Gly Val Gly Leu Asp Asn His Phe Gln Gln Thr His Cys Ser Ala 435 440 445 Asp Gly Ser Asp Lys Tyr Cys Arg Pro Ser Ala Asp Lys Pro Phe Ser 450 455 460 Tyr Tyr Lys Ser Asp Arg Val Ile Tyr Gly Glu Ser His Arg Leu Leu 465 470 475 480 Gln Ala Ala Phe Lys Lys Ser Phe Asp Thr Ala Lys Ile Arg His Asn 485 490 495 Leu Ser Val Asn Leu Gly Phe Asp Arg Phe Gly Ser Asn Leu Arg His 500 505 510 Gln Asp Tyr Tyr Tyr Gln His Ala Asn Arg Ala Tyr Ser Ser Asn Thr 515 520 525 Pro Pro Gln Asn Asn Gly Lys Lys Ile Ser Pro Asn Gly Ser Glu Thr 530 535 540 Ser Pro Tyr Trp Val Thr Ile Gly Arg Gly Asn Val Val Thr Gly Gln 545 550 555 560 Ile Cys Arg Leu Gly Asn Asn Thr Tyr Thr Asp Cys Thr Pro Arg Ser 565 570 575 Ile Asn Gly Lys Ser Tyr Tyr Ala Ala Val Arg Asp Asn Val Arg Leu 580 585 590 Gly Arg Trp Ala Asp Val Gly Ala Gly Leu Arg Tyr Asp Tyr Arg Ser 595 600 605 Thr His Ser Asp Asp Gly Ser Val Ser Thr Gly Thr His Arg Thr Leu 610 615 620 Ser Trp Asn Ala Gly Ile Val Leu Lys Pro Thr Asp Trp Leu Asp Leu 625 630 635 640 Thr Tyr Arg Thr Ser Thr Gly Phe Arg Leu Pro Ser Phe Ala Glu Met 645 650 655 Tyr Gly Trp Arg Ala Gly Val Gln Ser Lys Ala Val Lys Ile Asp Pro 660 665 670 Glu Lys Ser Phe Asn Lys Glu Ala Gly Ile Val Phe Lys Gly Asp Phe 675 680 685 Gly Asn Leu Glu Ala Ser Trp Phe Asn Asn Ala Tyr Arg Asp Leu Ile 690 695 700 Val Arg Gly Tyr Glu Ala Gln Ile Lys Asp Gly Lys Glu Glu Ala Lys 705 710 715 720 Gly Asp Pro Ala Tyr Leu Asn Ala Gln Ser Ala Arg Ile Thr Gly Ile 725 730 735 Asn Ile Leu Gly Lys Ile Asp Trp Asn Gly Val Trp Asp Lys Leu Pro 740 745 750 Glu Gly Trp Tyr Ser Thr Phe Ala Tyr Asn Arg Val Arg Val Arg Asp 755 760 765 Ile Lys Lys Arg Ala Asp Arg Thr Asp Ile Gln Ser His Leu Phe Asp 770 775 780 Ala Ile Gln Pro Ser Arg Tyr Val Val Gly Leu Gly Tyr Asp Gln Pro 785 790 795 800 Glu Gly Lys Trp Gly Val Asn Gly Met Leu Thr Tyr Ser Lys Ala Lys 805 810 815 Glu Ile Thr Glu Leu Leu Gly Ser Arg Ala Leu Leu Asn Gly Asn Ser 820 825 830 Arg Asn Thr Lys Ala Thr Ala Arg Arg Thr Arg Pro Trp Tyr Ile Val 835 840 845 Asp Val Ser Gly Tyr Tyr Thr Val Lys Lys His Phe Thr Leu Arg Ala 850 855 860 Gly Val Tyr Asn Leu Leu Asn Tyr Arg Tyr Val Thr Trp Glu Asn Val 865 870 875 880 Arg Gln Thr Ala Gly Gly Ala Val Asn Gln His Lys Asn Val Gly Val 885 890 895 Tyr Asn Arg Tyr Ala Ala Pro Gly Arg Asn Tyr Thr Phe Ser Leu Glu 900 905 910 Met Lys Phe 915 7 2139 DNA Neisseria meningitidis 7 atgaacaatc cattggtgaa tcaggctgct atggtgctgc ctgtgttttt gttgagtgct 60 tgtttgggcg gaggcggcag tttcgatctt gattctgtcg ataccgaagc cccgcgtccc 120 gcgccaaaat atcaagatgt tttttccgaa aaaccgcaag cccaaaaaga ccaaggcgga 180 tacggttttg caatgaggtt gaaacggagg aattggtatc cgcaggcaaa agaagacgag 240 gttaaactgg acgagagtga ttgggaggcg acaggattgc cggacgaacc taaggaactc 300 cctaaacggc aaaaatcggt tatcgaaaaa gtagaaacag acagcgacaa caatatttat 360 tcttccccct atctcaaacc atcaaaccat caaaacggca acactggcaa cggtataaac 420 caacctaaaa atcaggcaaa agattacgaa aattttaaat atgtttattc cggctggttt 480 tacaaacacg ccaaacgaga gtttaactta aaggtggaac ctaaaagtgc aaaaaacggc 540 gacgacggtt atatcttcta tcacggtaaa gaaccttccc gacaacttcc cgcttctgga 600 aaaattacct ataaaggtgt gtggcatttt gcgaccgata caaaaaaggg tcaaaaattt 660 cgtgaaatta tccaaccttc aaaaagtcaa ggcgacaggt atagcggatt ttcgggcgat 720 gacggcgaag aatattccaa caaaaacaaa tccacgctga cagatggtca agagggttat 780 ggttttacct caaatttaga agtggatttc cataataaaa aattgacggg caaactgata 840 cgcaacaatg cgaataccga taacaaccaa gccaccacca cgcaatacta cagccttgag 900 gctcaagtaa caggcaaccg cttcaacggc aaggcaacgg caaccgacaa accccaacaa 960 aacagcgaaa ccaaggaaca tccctttgtt tccgattcgt cttctttgag cggcggcttt 1020 ttcggcccgc agggtgagga attgggtttc cgctttttga gcgacgatca aaaagttgcc 1080 gttgtcggca gcgcgaaaac caaagacaaa cccgcaaatg gcaatactgc ggcggcttca 1140 ggcggcacag atgcggcagc atcaaacggt gcggcaggca cgtcgtctga aaacggtaag 1200 ctgaccacgg ttttggatgc ggtcgagctg aaattgggcg ataagaaagt ccaaaagctc 1260 gacaacttca gcaacgccgc ccaactggtt gtcgacggca ttatgattcc gctcttgccc 1320 gaggcttccg aaagtgggaa caatcaagcc aatcaaggta caaatggcgg aacagccttt 1380 acccgcaaat ttgaccacac gccggaaagt gataaaaaag acgcccaagc aggtacgcag 1440 acgaatgggg cgcaaaccgc ttcaaatacg gcaggtgata ccaatggcaa aacaaaaacc 1500 tatgaagtcg aagtctgctg ttccaacctc aattatctga aatacggaat gttgacgcgc 1560 aaaaacagca agtccgcgat gcaggcagga gaaagcagta gtcaagctga tgctaaaacg 1620 gaacaagttg aacaaagtat gttcctccaa ggcgagcgca ccgatgaaaa agagattcca 1680 agcgagcaaa acatcgttta tcgggggtct tggtacggat atattgccaa cgacaaaagc 1740 acaagctgga gcggcaatgc ttccaatgca acgagtggca acagggcgga atttactgtg 1800 aattttgccg ataaaaaaat tactggtacg ttaaccgctg acaacaggca ggaggcaacc 1860 tttaccattg atggtaatat taaggacaac ggctttgaag gtacggcgaa aactgctgag 1920 tcaggttttg atctcgatca aagcaatacc acccgcacgc ctaaggcata tatcacagat 1980 gccaaggtgc agggcggttt ttacgggccc aaagccgaag agttgggcgg atggtttgcc 2040 tatccgggcg ataaacaaac gaaaaatgca acaaatgcat ccggcaatag cagtgcaact 2100 gtcgtattcg gtgcgaaacg ccaacagcct gtgcaataa 2139 8 712 PRT Neisseria meningitidis 8 Met Asn Asn Pro Leu Val Asn Gln Ala Ala Met Val Leu Pro Val Phe 1 5 10 15 Leu Leu Ser Ala Cys Leu Gly Gly Gly Gly Ser Phe Asp Leu Asp Ser 20 25 30 Val Asp Thr Glu Ala Pro Arg Pro Ala Pro Lys Tyr Gln Asp Val Phe 35 40 45 Ser Glu Lys Pro Gln Ala Gln Lys Asp Gln Gly Gly Tyr Gly Phe Ala 50 55 60 Met Arg Leu Lys Arg Arg Asn Trp Tyr Pro Gln Ala Lys Glu Asp Glu 65 70 75 80 Val Lys Leu Asp Glu Ser Asp Trp Glu Ala Thr Gly Leu Pro Asp Glu 85 90 95 Pro Lys Glu Leu Pro Lys Arg Gln Lys Ser Val Ile Glu Lys Val Glu 100 105 110 Thr Asp Ser Asp Asn Asn Ile Tyr Ser Ser Pro Tyr Leu Lys Pro Ser 115 120 125 Asn His Gln Asn Gly Asn Thr Gly Asn Gly Ile Asn Gln Pro Lys Asn 130 135 140 Gln Ala Lys Asp Tyr Glu Asn Phe Lys Tyr Val Tyr Ser Gly Trp Phe 145 150 155 160 Tyr Lys His Ala Lys Arg Glu Phe Asn Leu Lys Val Glu Pro Lys Ser 165 170 175 Ala Lys Asn Gly Asp Asp Gly Tyr Ile Phe Tyr His Gly Lys Glu Pro 180 185 190 Ser Arg Gln Leu Pro Ala Ser Gly Lys Ile Thr Tyr Lys Gly Val Trp 195 200 205 His Phe Ala Thr Asp Thr Lys Lys Gly Gln Lys Phe Arg Glu Ile Ile 210 215 220 Gln Pro Ser Lys Ser Gln Gly Asp Arg Tyr Ser Gly Phe Ser Gly Asp 225 230 235 240 Asp Gly Glu Glu Tyr Ser Asn Lys Asn Lys Ser Thr Leu Thr Asp Gly 245 250 255 Gln Glu Gly Tyr Gly Phe Thr Ser Asn Leu Glu Val Asp Phe His Asn 260 265 270 Lys Lys Leu Thr Gly Lys Leu Ile Arg Asn Asn Ala Asn Thr Asp Asn 275 280 285 Asn Gln Ala Thr Thr Thr Gln Tyr Tyr Ser Leu Glu Ala Gln Val Thr 290 295 300 Gly Asn Arg Phe Asn Gly Lys Ala Thr Ala Thr Asp Lys Pro Gln Gln 305 310 315 320 Asn Ser Glu Thr Lys Glu His Pro Phe Val Ser Asp Ser Ser Ser Leu 325 330 335 Ser Gly Gly Phe Phe Gly Pro Gln Gly Glu Glu Leu Gly Phe Arg Phe 340 345 350 Leu Ser Asp Asp Gln Lys Val Ala Val Val Gly Ser Ala Lys Thr Lys 355 360 365 Asp Lys Pro Ala Asn Gly Asn Thr Ala Ala Ala Ser Gly Gly Thr Asp 370 375 380 Ala Ala Ala Ser Asn Gly Ala Ala Gly Thr Ser Ser Glu Asn Gly Lys 385 390 395 400 Leu Thr Thr Val Leu Asp Ala Val Glu Leu Lys Leu Gly Asp Lys Lys 405 410 415 Val Gln Lys Leu Asp Asn Phe Ser Asn Ala Ala Gln Leu Val Val Asp 420 425 430 Gly Ile Met Ile Pro Leu Leu Pro Glu Ala Ser Glu Ser Gly Asn Asn 435 440 445 Gln Ala Asn Gln Gly Thr Asn Gly Gly Thr Ala Phe Thr Arg Lys Phe 450 455 460 Asp His Thr Pro Glu Ser Asp Lys Lys Asp Ala Gln Ala Gly Thr Gln 465 470 475 480 Thr Asn Gly Ala Gln Thr Ala Ser Asn Thr Ala Gly Asp Thr Asn Gly 485 490 495 Lys Thr Lys Thr Tyr Glu Val Glu Val Cys Cys Ser Asn Leu Asn Tyr 500 505 510 Leu Lys Tyr Gly Met Leu Thr Arg Lys Asn Ser Lys Ser Ala Met Gln 515 520 525 Ala Gly Glu Ser Ser Ser Gln Ala Asp Ala Lys Thr Glu Gln Val Glu 530 535 540 Gln Ser Met Phe Leu Gln Gly Glu Arg Thr Asp Glu Lys Glu Ile Pro 545 550 555 560 Ser Glu Gln Asn Ile Val Tyr Arg Gly Ser Trp Tyr Gly Tyr Ile Ala 565 570 575 Asn Asp Lys Ser Thr Ser Trp Ser Gly Asn Ala Ser Asn Ala Thr Ser 580 585 590 Gly Asn Arg Ala Glu Phe Thr Val Asn Phe Ala Asp Lys Lys Ile Thr 595 600 605 Gly Thr Leu Thr Ala Asp Asn Arg Gln Glu Ala Thr Phe Thr Ile Asp 610 615 620 Gly Asn Ile Lys Asp Asn Gly Phe Glu Gly Thr Ala Lys Thr Ala Glu 625 630 635 640 Ser Gly Phe Asp Leu Asp Gln Ser Asn Thr Thr Arg Thr Pro Lys Ala 645 650 655 Tyr Ile Thr Asp Ala Lys Val Gln Gly Gly Phe Tyr Gly Pro Lys Ala 660 665 670 Glu Glu Leu Gly Gly Trp Phe Ala Tyr Pro Gly Asp Lys Gln Thr Lys 675 680 685 Asn Ala Thr Asn Ala Ser Gly Asn Ser Ser Ala Thr Val Val Phe Gly 690 695 700 Ala Lys Arg Gln Gln Pro Val Gln 705 710 9 33 DNA Artificial Sequence primer 9 tttcgcgacc acatgaaaag cgtcattcca tcc 33 10 28 DNA Artificial Sequence primer 10 gttctagagt ggcagcccta cctctgag 28 11 26 DNA Artificial Sequence primer 11 catatggtcc ctgataaaac tgtgag 26 12 28 DNA Artificial Sequence primer 12 cgatcgtgaa gtttggccaa acatactg 28 13 29 DNA Artificial Sequence primer 13 cgatcgaaac acgtatgaaa aatacttag 29 14 28 DNA Artificial Sequence primer 14 gttctagagt ggcagcccta cctctgag 28 15 26 DNA Artificial Sequence primer 15 catatggtcc ctgataaaac tgtgag 26 16 32 DNA Artificial Sequence primer 16 tctagattaa tctgttgggg cttctgggca tg 32 17 27 DNA Artificial Sequence primer 17 catatggaat gcaagcctgt gaagtgg 27 18 28 DNA Artificial Sequence primer 18 gttctagagt ggcagcccta cctctgag 28 

1. A non-neisserial cell expressing a neisserial iron uptake protein, wherein the iron uptake protein can be extracted from the cell under mild conditions and retains substantially the antigenicity of native iron uptake protein.
 2. A non-neisserial cell expressing a neisserial iron uptake protein wherein the iron uptake protein is located in an outer surface membrane of the cell.
 3. A cell overexpressing an iron uptake protein, wherein the iron uptake protein is located in an outer surface membrane of the cell.
 4. A non-neisserial cell according to any of claims 1 to 3 expressing a neisserial transferrin binding protein (Tbp) wherein:— said Tbp can be extracted from the cell under mild conditions; and said extracted Tbp retains substantially the antigenicity of native TbpA.
 5. A bacterial cell according to any of claims 1 to 4, expressing TbpA.
 6. A bacterial cell according to any of claims 1 to 5, expressing TbpB.
 7. A method of producing an iron uptake protein by expressing a recombinant iron uptake protein gene in a non-neisserial cell host such that the protein is expressed and translocated to a surface membrane of the host.
 8. A method according to claim 7 for producing a neisserial iron uptake protein selected from the group consisting of transferrin binding proteins (Tbps), lactoferrin binding proteins (Lbps), haemoglobin binding protein, enterobactin binding protein, vibriobactin binding protein, ferric siderophore binding protein, heme binding protein, hemin binding protein, chrysobactin binding protein, hydroxymate binding protein and pseudobactin binding protein.
 9. A method of producing a neisserial transferrin binding protein (Tbp) comprising: a. expressing a recombinant neisserial Tbp gene in a non-neisserial host such that Tbp protein is expressed and translocated to the cell membrane; b. under mild conditions, extracting the Tbp protein; and, optionally c. purifying said Tbp protein.
 10. A method according to claim 9 wherein the cell expresses TbpA.
 11. A method according to claim 9 or 10 wherein the cell expresses TbpB.
 12. A method according to any of claims 7 to 11 comprising extracting the Tbp by solubilising membrane bound Tbp in a non-ionic detergent solution.
 13. A method according to claim 12 wherein said non-ionic detergent is selected from the group consisting of an alkyl glucoside; n-octyl-β-D-glucopyranoside; TRITON® X100; ELUGENT®; dodecyl-maltoside; and n-octyl-β-maltoside.
 14. A method according to claim 13 comprising a low energy homogenisation step.
 15. A method according to any of claims 7 to 14, comprising breaking cells and cell membranes with a bead-beating apparatus.
 16. A method according to any of claims 7 to 15 wherein said native Tbp protein is purified by affinity chromatography.
 17. A method according to claim 16 wherein said affinity chromatography comprises using a transferrin-bound affinity matrix.
 18. A method according to claim 17 wherein said transferrin is human transferrin.
 19. A method according to any of claims 7 to 18 comprising culturing a cell according to any of claims 1 to
 6. 20. A method of preparing a vaccine, comprising obtaining an iron uptake protein according to any of claims 7 to 19 and combining said protein with a pharmaceutically acceptable carrier.
 21. Use of a cell according to any of claims 1 to 6 in manufacture of Tbp.
 22. Use of a cell according to any of claims 1 to 6 in manufacture of a vaccine for protection against neisserial disease and/or meningococcal disease and/or gonococcal disease.
 23. An expression construct comprising a nucleotide sequence encoding an iron uptake protein and a leader sequence directing the expressed protein to a surface membrane of the host.
 24. An expression construct according to claim 23, wherein the leader sequence comprises all or part of a neisserial leader sequence.
 25. An expression construct according to claim 23 or 24, wherein the leader sequence is the native leader sequence for the iron uptake protein.
 26. An expression construct according to claim 23, for expression of the protein in a host cell, wherein the leader sequence is all or part of a leader sequence native to the host.
 27. An affinity matrix for purification of Tbps comprising human transferrin or fragments thereof that bind Tbps.
 28. An affinity matrix according to claim 27 comprising human recombinant transferrin or fragments thereof.
 29. A method of purifying a Tbp, comprising eluting a Tbp-containing preparation through an affinity matrix comprising immobilized transferrin.
 30. A method according to claim 29 using an affinity matrix according to claim 27 or
 28. 31. A method according to claims 29 or 30 wherein the Tbp—containing preparation is obtained according to any of claims 7 to
 19. 32. A commensal neisseria expressing an iron uptake protein from a pathogenic neisseria.
 33. A commensal neisseria according to claim 32 expressing an iron uptake protein from a pathogenic Neisseria in an outer surface membrane of the commensal neisseria.
 34. A composition containing a Tbp, wherein at least 90 percent by weight of said Tbp is active Tbp.
 35. A composition according to claim 34, free of Tbp that is not capable of binding transferrin.
 36. A culture of cells which express a neisserial iron uptake protein, wherein the yield of said protein is at least 4 mg per litre of culture.
 37. A cell culture according to claim 36 wherein the protein is TbpA.
 38. A cell culture according to claim 36 wherein the protein is TbpB.
 39. A composition comprising an outer membrane vesicle preparation (OMV), wherein the OMV comprises an iron uptake protein and is prepared from a cell according to any of claims 1 to
 6. 40. A method of making a composition for vaccination, comprising obtaining an OMV from a cell according to any of claims 1 to
 6. 41. A method of producing a transferrin binding protein (Tbp) from a pathogenic Neisseria, comprising:— d. expressing a gene encoding the Tbp in a commensal Neisserial host such that Tbp protein is translocated to an outer surface membrane of the commensal host; e. extracting the Tbp under mild conditions; and f. optionally, purifying said Tbp protein.
 42. A method according to claim 41, comprising extracting an outer membrane vesicle preparation.
 43. A method according to claim 41 or 42, comprising expressing a N. meningitidis gene in N. lactamica.
 44. A method according to any of claims 41 to 43 wherein the Tbp is TbpA.
 45. A method according to any of claims 41 to 43 wherein the Tbp is TbpB.
 46. A method according to any of claims 41 to 45 comprising extracting the Tbp by solubilising membrane bound Tbp in a non-ionic detergent. solution. 